For centuries, it was accepted that artillery crews were at risk of going deaf from the laud noise made when their big guns fired. But in the last few decades, military medical researchers have confirmed what they long suspected; the loud noise (blast overpressure) felt by the gun crew did long term damage to other organs (lungs, intestinal tract) as well. The U.S. Army has developed a computer program, INJURY, which allows researchers to take overpressure data from various locations near and around a tank gun, or artillery or rocket system, and calculate the health risk to troops standing at those various positions and distances from the firing weapon. This has led to the calculation of which places behind the gun are safer, and to work on modifying protective vests to add more blast overpressure protection.